CVE-2026-100786

Analyzed Analyzed - Analysis Complete

Graphics Component Use-After-Free Sandbox Escape in Firefox

Publication date: 2026-09-29

Last updated on: 2026-10-05

Assigner: Mozilla Corporation

Description

Sandbox escape due to use-after-free in the Graphics component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

CVSS Scores

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Meta Information

Published

2026-09-29

Last Modified

2026-10-05

Generated

2026-10-19

AI Q&A

2026-09-29

EPSS Evaluated

2026-10-18

NVD

CVE-2026-100786

EUVD

EUVD-2026-88938

Affected Vendors & Products

Vendor	Product	Version / Range
mozilla	firefox	From 154.0.0 (inc) to 157.0.0 (exc)
mozilla	thunderbird	From 154.0 (inc) to 157.0 (exc)
mozilla	firefox	to 115.42.0 (exc)
mozilla	firefox	From 116.0 (inc) to 140.17.0 (exc)
mozilla	firefox	From 141.0 (inc) to 153.4.0 (exc)
mozilla	thunderbird	to 140.17.0 (exc)
mozilla	thunderbird	From 141.0 (inc) to 153.4.0 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-416	The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

Attack-Flow Graph

Executive Summary

This is a sandbox escape vulnerability caused by a use-after-free error in the Graphics component of Firefox. A use-after-free occurs when a program continues to use memory after it has been freed, potentially allowing attackers to execute arbitrary code or escape the browser sandbox.

Detection Guidance

This vulnerability is a sandbox escape due to use-after-free in Firefox's Graphics component. Detection requires checking Firefox version against patched releases: Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, or Firefox ESR 140.17. Use commands like 'firefox --version' or check package managers (e.g., 'apt list --installed | grep firefox' on Debian/Ubuntu). If your version is older, the system is vulnerable.

Impact Analysis

This vulnerability could allow malicious websites or code to break out of the browser sandbox, gaining access to the host system. This might lead to unauthorized code execution, data theft, or further compromise of the affected device.

Compliance Impact

This vulnerability could potentially lead to unauthorized access or data exfiltration due to sandbox escape, which may violate data protection requirements under GDPR or HIPAA if exploited.

Mitigation Strategies

Update Firefox to version ESR 153.4, Firefox 157, ESR 115.42, or ESR 140.17 or later to address the sandbox escape vulnerability.

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